Hitherto, an image forming apparatus is known which prints the separation category for a shredder or the like on a margin to achieve an efficient separation operation during printing. The apparatus determines the disposal categories from information such as quality or size of a sheet, kind of ink used for printing (color or monochrome), or printing ratio and prints the disposal categories on sheets. However, even though the disposal categories are printed on the sheet using the apparatus, for example, when the sheets are stapled during printing, the staple needs to be removed from the sheets for shredding during disposal, so that additional work cannot be reduced during disposal.
In addition, in recent years, an image forming apparatus is known which forms an image on a sheet using color-erasable toner of which color is erased by heating. When a sheet on which an image is formed by color-erasable toner is heated, the image on the sheet can be erased, thereby the sheet can be reused. However, even though the image is formed using the color-erasable toner, for example, when the sheets are stapled, the staple needs to be also removed from the sheets during color erasure. As such, in the image forming apparatuses according to the related art, additional work cannot be reduced during disposal or reuse processes.